Tuning mechanism for a helix/cylinder antenna

ABSTRACT

There is disclosed a tuning element configuration for a helix/cylinder (inductance/capacitance) type antenna, the tuning element comprising a shorting tube assembly which includes a lower tube drive assembly, an upper guide roller assembly and an intermediate shorting brush assembly arranged therebetween. The tube drive assembly consists of a lower shorting brush arrangement and a drive roller arrangement, the latter of which is made up particularly of a simple stamped and screw-machine parts to provide a configuration which is superior to the prior art both structurally and electrically while being significantly less costly. Similarly, the upper guide roller assembly consists of an upper shorting brush arrangement and a guide roller arrangement which is made up of simple stamped and screw-machine parts in a less costly but electrically and structurally superior configuration. Provision is made for a novel construction of shorting brushes which go to make up the intermediate shorting brush assembly and which also constitute the major parts of the upper and lower shorting brush arrangements.

United States Patent Majkrzak et al.

[ TUNING MECHANISM FOR A HELIX/CYLINDER ANTENNA Inventors: Charles P. Majkrzak, Nutley;

Michael S. Polgar, Oceanport, both of NJ.

International Telephone and Telegraph Corporation, Nutley, NJ.

Filedz Feb. 5, 1973 Appl. No.: 329,792

[73] Assignee:

[56] References Cited UNITED STATES PATENTS Primary ExaminerEli Lieberman Lombardi 343/895 Attorney, Agent, or Firm-John T. Ol-lalloran; Me-

notti J. Lombardi, Jr.

VARIABLi CAPAC/TANC' VAR/ABLA' INDUC TANC July 16, 1974 [5 7] ABSTRACT There is disclosed a tuning element configuration for a helix/cylinder (inductance/capacitance) type antenna, the tuning element comprising a shorting tube assembly which includes a lower tube drive assembly, an upper guide roller assembly and an intermediate shorting brush assembly arranged therebetween. The tube drive assembly consists of a lower shorting brush arrangement and a drive roller arrangement, the latter of which is made up particularly of a simple stamped and screw-machine parts to provide a configuration which is superior to the prior art both structurally and electrically while being significantly less costly. Similarly, the upper guide roller assembly consists of an upper shorting brush arrangement and a guide roller arrangement which is made up of simple stamped and screw-machine parts in a less costly but electrically and structurally superior configuration. Provision is made for a novel construction of shorting brushes which go to make up the intermediate shorting brush assembly and which also constitute the major parts of the upper and lower shorting brush arrangements.

2| Claims. 11 Drawing Figures METALLIC S CYLINDER 5 UPPER s/wn n/vq BRUSH 9 f. cu/0e nous/Q a INTERMED/A TE PAIENTED JUL 1 61914 VARIABL CAPACITANCE VAR nae/.5 INDUCTANC SHEET 1 OF 6 l igu METAL 4 IC CYLINDER 5 UPPER SHOR r/A/q BRUSH 9 0105 ROLLER a SHORT/NC TUBE ASSEMBLY I l v TERMED/A r BRUSH 70.

ONE OF NORM/144,7 s/x OR EIGHT 0R/ w/vc ROLLER 3 L0 wER SHOR TING eRusH 7 HELIX a 5/. 6C TR/CAL F650 POINT 6 SHAFT 4 PATENTEU JUL 1 6 I974 sum 2 nr 6 PATENIED JUL 1 51974 sum u 0F 6 .TRAV'L L/M/T 5:07 5m! ROLLER SHAFT 54 %QADIAL TRAVEL GUIDE SLOT 53a! 57a/ 5743 POST ASSEMBLY SHAFT 2 57a? END PLATE IIAI MOUNT/NC LATE A 53a M16 PLATE 553b ELECTRIC BRUSH TORSION SPAM/(,- 5

HELIX TURN 2 PITCH-CONTROL SPACER 55 5755: 57b TORSION SPRING POST RAD/Al. LOADING TORSION SPRING 57b TRAVEL L/M/T SLOT 5 a/ RAD/AL TRAVEL cum: SLOT 53 kouek 52 AND PLATE SPAC'R 56 ROMA-R SHAF754 /TEHELIX TURN a swam/cm BRUSH TORSION spa/m; 58 MOUNT/NC PLA re 'A 53 TORSIION SPRING Posr ANO PAT SPACER 5 SHEET 5 BF 6 PATENIEU JUL 1 s 1914 TUNING MECHANISM FOR A HELIX/CYLINDER ANTENNA BACKGROUND OF THE INVENTION This invention relates to transmitting antennas of primarily the tunable inductive/capacitance type in the 2 to 30 MHz range for shipboard and submarine use, and more particularly to an improved tuning arrangement for such antennas.

Such antennas have been disclosed in co-pending US. Application Ser. No. 324,607 filed Ja. 18, 1973, the subject matter of which, insofar as it is relevant to the instant invention, is incorporated herein by reference.

In such antennas, an inductive helix is arranged in series and physically end-to-end with a'capacitive cylinder element. The tuning element is, by design, a driven metal tube with one end contacting the helix internally through an assembly of graphite or metallized graphite brushes, the other end contacting the cylindrical tube internally, and a multiplicity of logically-spaced intermediate graphite or metallized graphite brushes alternately contacting both the helix and the cylinder as required in its travel over the tuning range. Such an arrangement, as designed for available manufacturing facilities of the early l960s, is quite costly when compared to possible designs geared to presently available manufacturing facilities. The so-designed prior art arrangements are replaceable by the disclosed novel shortingtube tuning element arrangement, which is a principal object of this disclosure.

Formally, the tuning element construction and design evolved about costly milling machine and lathe operations. It is an object of this invention to provide, in place of such operations and resulting parts, simple sheet metal stampings and simple screw-machine parts which go to make up a structurally and functionally superior lower or tube drive assembly portion of the shorting tube tuning element.

Similarly, it is an object of this invention to. replace the typical milled and turned parts of the guiding upper end of the shorting-tube assembly of the prior art with simple sheet-metal stampings and screwmacine parts which when assembled comprise a structurally and functionally superior upper or guide-wheel assembly portion of the shorting tube element. 1

Further, it is the practice of the prior art to have intermediate brush configurations (usually required in quantities of six to eight per tuning element) fabricated of a multiplicity of complex milled and turned parts. It is, therefore, another object of this invention to provide simple screw-machine parts of extruded rod which are structurally and functionally superior to the prior art arrangements.

The foregoing is indicative in but a general way of the great differences between the prior art and the improvements disclosed herein.

SUMMARY OF THE INVENTION According to the broader aspects of this invention, there is provided in a drive assembly adapted to function within a helically coiled wire, the arrangement comprising first plate means including a first pair of flat plates arranged to be substantially in parallel and a plurality of roller assemblies, each having a roller and being mounted between said first pair of plates, each said roller extending partially beyond said first plates for engagement with said helix and being predeterminably positioned so as to have the rollers of said plurality of assemblies helically staggered between said first plates.

Moveover, there is provided in a shorting apparatus for an antenna tuning element, a guide arrangement adaptedto function within and engage a cylindrically shaped surface, comprising plate means including a first pair of flat hexagonally-shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer mounted between said hexagonallyshaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equaldimension defining the substantially parallel separation between said first plates.

There is also provided according to the invention apparatus comprising a shorting brush configuration including a tubular outer structure and a shorting brush element mounted within said tubular structure so as to partially protrude therefrom and to be resiliently displaceable therein.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other objects of this invention will become more apparent and the invention itself will be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 schematically illustrates in a partial sectional side view a helix/cylinder type antenna incorporating a shorting tube assembly as its tuning element;

FIGS. 2A and 2B are respectively schematic side and v perspective views of the shorting tube assembly which comprises the antenna tuning element according to the invention;

FIG. 2C illustrates in perspective view the lower or tube drive assembly portion of the shorting tube assembly of FIGS. 2A and 2B;

FIGS. 3A and 3B illustrate in diagrammatic side and perspective views respectively the drive roller arrangement comprising part of the lower tube drive assembly of the shorting tube assembly according to the invention;

FIG. 3C illustrates in a partial sectional end view the lower drive roller arrangement of FIGS. 3A and 38;

FIG. 4 illustrates in perspective the upper guide roller I DESCRIPTION OF THE PREFERRED EMBODIMENTS(S In FIG. 1, the antenna essentially comprises an inductive helix 2 and a capacitive cylinder 5. The ration of effective inductane and effective capacitance to space determines the resonant frequency of the radiator. As

stated, the tuning arrangement in the disclosed example antenna situation comprises a novel shorting-tube assembly, in conjunction with an associated drive shaft 4. The purpose of the shorting-tube assembly is to electrically short-out turns in the helix 2 of the seriestype inductive/capacitive radiator, which is electrically fed at tap point 6. FIG. 1 schematically illustrates such a shorting element 1. When it is required to tune the radiator to a particular frequency, by varying the ration of inductance to capacitance to the proper amount, a

'reversable motor (not shown) rotates the drive shaft 4 for example in the direction indicated by arrow 4a via an appropriate transmission system (also not shown) which, in turn, causes the shorting-tube assembly 1 to also rotate.

That portion of helix 2 between the feed point 6 and the first brush 7 on the shorting tube primarily controls the effective inductance; while the combination of the metallic cylinder 5, the portion of the shorting-tube 1 extending below the cylinder 5, and also the shorted helix turns above the shorting brush 7, primarily controls the effective capacitance to space.

A set of grooved drive rollers, depicted in FIG. 1 by a single drive roller 3, is attached to and made part of the shorting-tube assembly 1 and configured so as to engage and roll on the helix 2, which causes the shorting-tube assembly to advance or withdraw along the drive shaft 4 at a rate consistent with the revolutions and pitch of the helix 2. The drive rollers3, in conjunction with a lower shorting brush arrangement 7 comprise the tube drive assembly 20 (See also FIG. 2A).

The rollers 3 are arranged to travel radially within a I limited range, and are spring-loaded against the helix 2, so that compensation may be effected from the normal working tolerances and irregularities of the helix. In addition, the rollers 3 are positioned and spaced so as to distribute and transmit vertical shock loads equally over and through several helix, turns, which will be more thoroughly treated hereinafter.

At the opposite or upper end of the shorting tube assembly l is provided a similar roller arrangement as part of the upper guide roller assembly 30 (FIG. 2A), which assembly comprises a set of guide rollers, flat rather'than grooved as in thecase of the tube drive assembly rollers 3, as depicted in FIG. 1 by guide roller 8, and the upper shorting brush arrangement 9. This guide assembly 30 is intended to locate and guide the upper end of the shorting tube assembly always within the cylindrical portion 5 of the antenna; as such it is designed so that the guide rollers 8 and the upper shorting brush 9 make continual contact with the interior of the cylinder 5.

In between the driving and guiding assemblies 20 and 30 and protruding radially from the central portion of the shorting assembly 1 are a plurality of predeterminably-spaced intermediate shorting brush configurations, comprising an intermediate shorting brush assembly 40, depicted by the lone intermediate brush configura tion 10. The purpose of the intermediate brushes is detailed in the following operational characteristics of a helix/cylinder type antenna. Although the shorting assembly 1 in any given position renders a number of helix turns electrically irrelevant in terms of antenna resonant frequency, these turns do in fact, couple into the field of the active helix as a shorted transformer and resonate at particular frequencies completely out of phase with that of the prime active helix. In such in- 4. stances, the radiating properties of the antenna degrade considerably. To prevent this, the intermediate brushes 10 are strategically located between the main shorting brushes on the upper and lower portions of the shorting tube assembly so as to always present non-resonating sections of shorted helix with respect to the frequency to which the antenna is tuned at that particular setting and instance. Six or'eight intermediate brushes are usually required for a helical antenna operating in-the 2 to 30 MHZ range. In such circumstances, the out of phase characteristics are negligible. The intermediate brushes, also, are positioned in relationto the pitch of the helix 2 such that as the shorting assembly is rotated up or down the antenna, the intermediate brushes 10 are in full contact with a helix turn until antenna frequency selection takes one or more of same up into the antenna cylindrical portion 5.

The combination, therefore, of the tube drive assembly 20, the guide roller assembly 30, and the intermediate brushes assembly 40 constitute the shorting-tube assembly 1 in full.

The practical length of a capacitive cylinder 5 is usually about the same as the length of the inductive helix 2. When the lower shorting brush 7 is at the one extreme near the feed point 6 with all the helix 2 shorted-out, the upper shorting brush 9'is usually contacting the lowermost internal portion of the cylinder 5. In such an attitude, the antenna is resonating at its highest frequency in the various modes of 1/4'-wave, 3/4-wave, 5/4-wave, etc. When the lower shorting brush 7 is at the other extreme near the top of the helix 2 with allthe helix 2 active, the upper shorting brush 9 is contacting the uppermost internal portion of the cylinder 5. In such an attitude, the antenna is resonating at its lowest frequency in the l/4-wave mode. This permits an antenna of reasonable and practical length to be tuned from about 2 to about 15 MHz in the l/4-wavemode and from about 10 to about 30 MHz in the 3/4-wave mode.

The shorting tube assembly according to the invention is shown schematically in side view in FIG. 2A and in perspective view in FIG. 2B. A hollow central tubular portion 41 is provided upon which are mounted radially with respect to the longitudinal axis thereof intermediate brush configurations 10, with the tubular center portion 41 having at its ends flanged sections 42, 43 respectively. To the lower flanged section 42 is coupled the shorting-tube drive assembly 20, and correspondingly the guide roller assembly 30 is coupled to the upper flanged portion 43. FIG. 2A illustrates in detail via a partial section the novel construction of an intermediate brush configuration 10. The brush configuration 10 is comprised of a piece of extruded hollow rod 11 cut to a predetermined length and rounded off at the one end destined to be the free end. This piece of rod 11 is mounted via its other end to the central tubular portion 41 of the shorting tube assembly 1 (e.g., by

welding) in a flattened-out area 12 in the exterior of tubular portion 41. Prior to the mounting, however, a pair of holes 13 are drilled in the flattened-out area 12 and also a larger hole 14 is drilled in tubular portion 41 proximate the flattened-out portion 12. A pair of high power-handling graphite brushes 15 are positioned within the rod 11, each with one end thereof protruding from the open free end of rod 11, and with the other end thereof coupled to a spring 16, which in turn surrounds a conductor 17 extending from the other end of the graphite brushes into the interior of tubular portion 41 via holes 13 respectively. The conductors 17 are run back through hole 14 to the exterior of tubular portion 41 to be fixedly coupled to the side of rod 11, as may be more clearly seen in FIG. 28 at 18. The springs 16 are of course unable to pass through holes 13 and, therefore, remain confined to the rod 11 interior. The purpose of the springs 16 is to allow intermediate brush a certain amount of radial flexibility in allowance of system tolerances etc., under a pressure which insures continual good contact with either the helix 2 and cylinder 5. As may be seen from FIG. 2A and the above description, the intermediate brushes 10 are comprised of a minimum of inexpensive and easily-assembled pieces, which provide a minimum of system friction and wear, as well as requiring no adjustment and virtually no maintenance. r

The tube drive assembly 20, which will now be described with reference to FIGS. 2A2C, as stated, forms the lower portion of the shorting-tube assembly 1 and couples to flange portion 42 of central tubular portion 41. Drive assembly 20 is comprised of two sections, i.e., the drive roller arrangement 50, coupled adjacent to flange 42, and the lower shorting brush arrangement 60, coupled to the drive roller arrangement 50. The drive roller and shorting brush arrangements 50 and 60 are firmly held to each other and to flange 42 by way of a series of three threaded shafts 21 with suitable end pieces 22; shafts 21 are arranged to pass longitudinally through arrangements 50 and 60 and define a substantially equal-angular triangle formation as viewed from the lower end of the shortingtube assembly l. The lower end of each shaft 21 is intended to be secured by end piece 22 which is received in a recessed area 61 of lower shorting brush arrangement 60. The other end of each shaft 21 is secured by a piece 23 as shown.

The lower shorting brush arrangement60 is comprised primarily of a cylindrical member 62, presenting at the lower end of the shorting-tube arrangement 1 a flat major surface 62a, punctuated by a series of recesses and apertures. Among these are the recesses 61 and associated apertures for threadedshafts 21. There is of course also provided a large centrally located aperture 64 for the main drive shaft (not shown) of the entire tuning element. The flat major surface 62a is further punctuated by a somewhat kidney-shaped recess 65 (see in particular FIG. 2C), concentrically located between the outer periphery of cylindrical piece 62 and the centrally located aperture 64. To this cylindrical piece 62 are mounted a series of three high power capacity shorting brush units 66 which collectively make up the lower shorting brush facility. See in particular FIGS. 2A and 2C. The brush units are each mounted (e.g., by soldering) into respective recesses radially drilled in the outer periphery 62b of cylindrical piece 62, and spaced apart a predetermined small amount. The construction of the shorting brushes 66 is quite similar to that as described with respect to intermediate brushes 10, with these important differences. Firstly, the outer shell 66a is intended to be of a smaller diameter extruded rod than that used in the construction of the intermediate brushes 10. Moreover, only one graphite brush 66b is used, which brush is grooved at the free end to specifically follow and make the best possible contact with the helix 2 wire. Lastly, the conductor 66c protruding from the bottom of grooved graphite brush 66b (not shown) is passed through a channel 68 connecting recess 67 with kidney-shaped recess to be secured to the bottom of the latter recess at 69.

Looking to FIG. 2C, the left side shorting brush 66 is the brush which determines the initial shorting point on the helix 2; and therefore its position determines the antenna resonant frequency. However, the power capacity of the antenna would be unduly limited by the power handling capability of this one lower shorting brush. Therefore, the other two lower shorting brushes 66 have been added to share this power load and to remove this antenna power limitation. The three brushes 66 act as in parallel to create the required high powerhandling short on the same helix turn, with the leftmost or lowest (in terms of the helix 2) brush 66 constituting, as stated, the antenna frequency-determining short position.

Since transmitting antennas are driven at high power levels that cause high currents to flow between the inductor 2 and capacitor 5, and because the contacts between these elements are movable, graphite and metallized graphite brushes of high current-carrying capacity are used. Since contact resistance and wear are quite important, these brushes are usually of a special com position; by way of example, a silver-graphite mixture. It is necessary to a degree to stagger the three shorting brushes 66 longitudinally (with respect tothe longitudinal axis) to compensate for the pitch of the helix 2 between the left-hand and right-hand brushes 66, to follow the helix 2 without creating contact problems or excessive wear. The necessary contact pressure is, again, provided by springs (not shown) just as in the case with intermediate brushes 10.

In describing now the drive roller arrangement 50 of the tube drive assembly 20, reference is made particularly to FIG. 2A and FIGS. 3A-3C. The drive roller arrangement 50, like the guide roller arrangement 70 of the upper guide roller assembly 30 (to be described in greater detail hereinafter) is comprised of a series of eight simple common parts according to the following listing:

end plates mounting plates shafts (for rollers) posts (assembly shafts) rollers The drive roller arrangement 50 is defined in its outer aspects by a pair of identical flat, hexagonal-shaped end plates, end plate A (51a) and end plate B (51b). End plate A (510) is intended to be adjacent to and firmly in contact with the backside 62c of cylindrical portion 62 of the lower shorting brush arrangement 60, and end plate B (51b) is intended to be adjacent to and firmly in contact with flange 42 of central tubular portion 41. Each of the end plates 51a and 51b (FIGS. 3B and 3C in particular) has six elongated apertures Slal, 51b1 each of which apertures extends radially inward toward the center of the plate from a point proximate a corresponding one of the hexagon vertices. Equally spaced between adjacent ones, of the elongated apertures 51a], 51b1 is found a substantially circular aperture 51a2, 5lb2. Lastly, end plates 51a and have the same apertures, designated 53al, 53a2, 53a3 and 53b1, 53b2, 53123 respectively, and at the same cations as described above for end plates 51a and 51b, with the exception that the six elongated apertures 53al and 53bl are somewhat narrower than their end plate counterparts and are open-ended to communicate with the periphery of the hexagonal mounting plates at the vertices thereof. Mounting plates 53a and 53b are fixedly spaced apart in parallel primarily by plate spacers 56 (FIG. 3A) mounted on the posts or assembly shafts 21.

Between these two mounting plates 53a and 53b are arranged in predetermined manner and pitch (to be described in greater detail in reference to FIGS. 5A-5C) a series of six grooved rollers 52. The rollers are fixedly maintained between the mounting plates 53a and 53b by particular spacer sets 55, with the axes of rotation of the rollers and their respective shafts of rotation 54 being substantially parallel to the central longitudinal axis of the shorting tube assembly 1. The rollers 52'are grooved so as to ride on the helix 2 (see in particular FIGS. 1 and 3A); the radius of curvature of the groove for the rollers 52 is slightly larger than the radius of curvature of the helix wire to allow the rollers to follow the helix pitch without becoming detrained, and without the requirement that they be mounted to conform exactly with the helix pitch. However, in contemplating increased rotational speeds commensurate with possible requirements for very rapid tuning, any danger of detrainment is overcome by the simple device of swiveling the two end plates 53a and 53b relative to one another a predetermined amount, i.e., one clockwise and the other counter-clockwise; this has the effect of angling the roller shafts away from a perpendicular orientation relative to the parallel end plates and can, in fact, angle the roller shafts so that the rollers will conform to the pitch angle of the helix. This in turn serves to orient the rollers to better follow the pitch of the helix.

The roller spacer sets together with the associated wheels 52 provide a total spacing equal to that provided by the plate spacers 56 in maintaining the mounting plates 53a, 53b in substantially parallel relationship. The spacer sets 55 are each designed to locate an associated roller 52 at a particular placement between the mounting plates 53a, 53b relative to the other rollers 52 such that the grooved wheel formation constitutes a staggered relationship substantially equal to the pitch of the helix 2 on which the rollers ride. This will be described in greater detail hereinafter with reference to FIGS. 5A-5C As may be particularly seen in FIGS. 38 and 3C, the shaft 54 of each roller 52 is initially arranged to pass substantially perpendicularly through associated narrow/open-ended radial travel guide slots 53a1,-53b1 in the mounting plates 53a, 53b, and through the respective travel limit slots Slal, 51bl in the end plates 51a, 51b. By virtue of the fact that slots 53a1, 53121 are open-ended the combined package of roller 52, associated spacer set 55 and associated roller shaft 54 may be placed in the position shown as an assembled unit most radial position by way of radial loading torsion springs 57a located between the end and mounting plates 51a and 53a, and also 57b located between the end and mounting plates 5 lb and 53b. A radial loading torsion spring 57a, 57b is located between each of the wheels 52 (12 springs in all) and wound about the post or assembly shaft 21 between the wheels running between end and mounting plate apertures 51a2, 53a2, 51b2, 53b2. The radial loading torsion springs 57a, 57b are wound in such a way as to have two extensions, for example 57a2, 57a3 (FIG. 3A) from the center portion 57al, each of which is intended to continually press against one of the two adjacent roller shafts 54 to urge the latter radially outward.

The rollers'52 are arranged, as stated, totravel radially within a limited distance, and are spring-loaded against the helix 2, so that compensation may be effected for the normal working tolerances and irregularities of the helix. In addition, the rollers 52 are positioned and spaced so as to distribute and transmit vertical shock loads equally over and through several helix turns. Although each roller is metallic and electrically conductive, it is not necessary to insulate it from the. shorting tube 1 since it is electrically useful and acts like a shorting contact. However, each roller 52 is lubricated with an oil film that forms an insulating bar: rier; but since the current flow is relatively low at their locations, a low-resistant electrical continuity can be and is readily made through phosphor-bronze or beryllium-copper spring-wire brushes or electric brush torsion springs 58 at each roller 52.

The electric brush torsion springs 58 are in this example embodiment limited to three in number. They are arranged via their wound central portion 58a about every other post or assembly shaft 21, and-have two extensions 58a, 580 (FIG. 3A), each intended to be urged into continual contact with the grooves of one of the rollers adjacent thereto. In this way each roller 52 is contacted.

The upper guide roller assembly 30 (FIGS. 2A, 2B and 4) is for the most part constructed the same as the tube drive assembly 20 with these important differences. Firstly, inasmuch as the guide roller assembly 30 is intended to be permanently housed within the cylindrical portion 5 of the antenna, and to remain in continual contact with the internal side surface thereof, the wheels 71 of the guide roller arrangement have a flat rolling surface rather than being grooved, in order to be flush and in stable contact with the cylinder 5 interior. Moreover, the wheels 71 may be constructed of a dielectric material.

As it is not required that the upper guide roller assembly 30 be trained on the helix 2, less wheels are needed to provide a rolling function, and therefore every other roller position about the hexagon-shaped guide roller arrangement 70' is replaced by a spacer 72. Moreover, the wheels 71 are not required to be staggered in pitch, and therefore all are provided with the same spacer sets 73.

There are provided, as is the case with lower shorting brush arrangement 60, three shorting brushes 81 in the upper shorting brush arrangement of the guide roller assembly 30; however, each of the brushes 81 has a flat graphite head 81a rather than a grooved head, and also the three brushes 81 are mounted equally spaced apart around the periphery of the-upper brush arrangement 80.

It is not required that electric brush torsion springs be included in the guide roller arrangement 70 of the upper guide roller assembly 30 as equivalents to the electric brush spring 78 of the drive roller arrangement 50 of the tube drive assembly 20. Also as may be seen most clearly in FIG. 4', the central aperture 82 running through the upper guide roller assembly 30 begins in a recess of a larger opening 83 in the upper shorting brush arrangement 80. The shorting conductors 84 of the brushes 81 are affixed to this recess at points 85.

Notwithstanding the above indicated differences between the lower tube drive assembly 20 and the upper guide roller assembly 30, it may be seen from the description above that these two assemblies are composed of inexpensively made and assembled parts, to form configurations superior in performance and cost to that provided by the prior art.

Referring to FIGS. 5A,5C, there is graphically depicted therein in sequence the roller-spacer set arrangement of the drive rollers 52' of the tube driveassembly 20. The illustration shows the rollers/spacers as a function of helix pitch per one turn of the helix. Each roller positioned about the hexagonally-shaped lower drive roller arrangement 50 is depicted in FIGS. 5A-5C as a roller station (1) (6). FIG. 5A shows each roller in its intended position relative to a set of five unit washers of 1/6 pitch in thickness each. The spacer set is simply an arrangement of five common washers on each roller shaft so as to locate that particular roller-at its required corresponding level with respect to the pitch of the helix 2 as shown. The washer, of course, can be of a unit length as shown in FIG. 5A wherein each shaft would then bear five washers properly allocated to produce the required roller levels, or the pitchcontrol spacer can be ofthe multiple-unit length required to maintain the roller at its proper level as shown in FIG. 5B.

There is a decided advantage gained from having the wheels 52 ride two turns of the helix 2 simultaneously (FIG. 5C) rather than one turn as shown in FIGS. 5A and 5B. This advantage comes from the fact that the antenna'arrangement is often exposed to jarring vertical movement (vertical shock), which when one considers the shorting tube assembly, translates into the fact that with practically all the load fromthe mass of the shorting tube assembly 1 being supported via the wheels 52 riding on the helix 2, the latter could be bent or otherwise structurally or electrically deformed. If the wheels are distributed in pitch so as to simultaneously ride on two adjacent helix turns, then the abovementioned mentioned load is far better distributed, and the danger of the helix 2 being bent or otherwise deformed out of shape (thus possibly hampering or preventing further movement of the shorting tube assembly 1) is greatly reduced. This-is accomplished according to FIG. 5C wherein pitch control spacers of pitch-plus-multiple unit lengths are provided, in which every other roller 52 is staggered to accommodate the two adjacent helix turns. I i There has been described herein a tuning element configuration for a helix/cylinder (inductance/capacitance) type antenna comprising a shorting tube assembly which includes a lower tube drive assembly, an upper guide roller assembly and an intermediate shorting brush assembly arranged therebetween. The tube drive assembly consists of a lower shorting brush arrangement and a drive roller arrangement the latter of which in particular is madeup of simple stamped screw-machine parts to provide a configuration which is superior to the prior art both structurally and electrically, yet is significantly less costly. Similarly, the upper guide roller assembly consists of an upper shorting brush arrangement and a guide roller arrangement the latter of which particularly is made up of simple stamped and screw-machine parts in a less costly but electrically and structurally superior configuration. Provision is made for a novel construction of shorting brushes which brushes go to make up the intermediate shorting brush assembly and constitute as well the major parts of the upper and lower shorting brush arrangements.

While the principles of this invention have been described above in connection with specific apparatus, it is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention as set forth in the objects thereof and in the accompanying claims.

What is claimed is:

1. In a drive assembly adapted to function within a helically coiled wire, the arrangement comprising first plate means including a first pair of flat plates arranged to be substantially in parallel and a plurality of roller assemblies, each having a roller and being mounted between said first pair of plates, each said roller assembly including an axle arranged to extend between said first plates proximate the peripheries of the latter, with the associated roller being arranged on said axle, and a roller spacer set arranged on said axles and between said first plates to helically position said rollers between said plates to extend outwardly thereof and engage the helically coiled wire.

2. The arrangement of claim 1 wherein said roller assemblies are mounted between said first plates to be equally spaced apart from orie another.

3. The arrangement of claim 2 wherein each said spacer set includesa spacer member of predetermined size on either or both sides of the associated roller so as to provide the latter with said predetermined position between said first plates.

4. The arrangement of claim 3 wherein said spacer member is comprised of one or more unit-sized spacers, the unit size of which is predetermined by the pitch of said helix and the number of roller assemblies employed.

5. The arrangement of claim 1 wherein said rollers are arranged to be staggered helically in pitch between said first plates by way of said spacer set so as to have said rollers engage a plurality of adjacent helix turns simultaneously.

6. The arrangement of claim 5 wherein in the case of said rollers engaging a pair of adjacent helix turns simultaneously, the roller assemblies are arranged to have alternate ones thereof engage the same one of said pair of helix turns.

7. The arrangement of claim 1 further comprising second plate means including a second pair of flat plates arranged to be substantially, parallel, and to have said first plates therebetween and substantially in parallel therewith, said first and second plate means being mounted together to form an integral unit.

8. The arrangement of claim 7 wherein said roller assemblies are mounted between said first and second pairs of plates in a manner providing a capability of translational displacement substantially parallel to the plane of said first and second plates, and further comprising spring means biasing said roller assemblies outward toward the periphery of said first plate means.

9. The arrangement of claim 8 wherein said first and second pairs of plates are hexagonally shaped with the vertices thereof substantially aligned, and wherein the axle of each said roller assembly is arranged to engage said first and second pairs of plates proximate respective ones of the aligned plate vertices.

10. The arrangement of claim 9 wherein said spring means includes a plurality of springs mounted between said first and second plate means, each of said springs being arranged substantially between two adjacent roller assemblies so as to urge said adjacent roller assemblies toward the periphery of said first and second plate means.

11. The arrangement of claim 10 wherein said spring means include a first plurality of springs arranged between the pair of plates comprised of one each of said first and second pairs of plates and a second plurality of springs arranged between the pair of plates comprised of the other one of said first and second pairs of plates, and wherein a respective one of each of said first and second pluralities-of springs is arranged to be between each adjacent pair of roller assemblies to engage same proximate the respective opposite ends thereof to bias the latteroutwardly.

12. The arrangement of claim 11 further including mounting means in the form of a plurality of equally spaced assembly posts extending between said first and second pairs of plates for mounting said first and second plate means into an integral unit, and wherein the individual ones of said pluralities of springs are mounted on said posts. 13. The arrangement of claim 12 wherein one of said posts is located between each adjacent pair of roller assemblies and equidistant therefrom, and wherein'said springs are correspondingly positioned between adjacent roller assemblies.

14. The arrangement of claim 10 wherein said first and second plates are each provided with a plurality of elongated apertures each extending radially inward from a point proximate a respective one of said hexagon vertices, for permitting the axles of said roller assemblies to extend through said plates and for permitting said roller assemblies a predetermined amount of translational movement in the radial direction relative to render the electrical potential difference between said rollers and said plates zero,

12 17. The arrangement of claim 1 further including a lower shorting brush arrangement coupled to said drive assembly arrangement, the combination forming a lower drive assembly of a shorting tube assembly comprising a tuning element in an antenna having a helical radiating element.

18. A tuning element comprising an integrally constructed shorting assembly having proximate one end thereof a drive arrangement including a set of drive rollers and first shorting brush configuration, proximate the other end thereof a guide arrangement including a set of guide rollers and a second shorting brush configuration, and an intermediate brush arrangement predeterminably arranged as to said shorting assembly be tween said drive and guide arrangements, said guide arrangement being adapted to function within and engage a cylindrically shaped surface and comprising plate means including a first pair of flat hexagonally shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies 'each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer mounted between said hexagonally shaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equal dimension defining the substantially parallel separation between said first plates.

19. A tuning element comprising an integrally constructed shorting assembly having proximate one end thereof a drive arrangement including a set of drive rollers and a first shorting brush configuration, proximate the other end thereof a guide arrangement including a set of guide rollers and a second shorting brush configuration, and an intermediate brush arrangement predeterminably arranged as to said shorting assembly between said drive and guide arrangements, wherein said intermediate brush arrangement includes a tubular outer structure and a shorting brush element mounted within said tubular structure so as to partially protrude therefrom and to be resiliently displaceable therein, and wherein said guide arrangement is adapted to function within and engage a cylindrically shaped surface and comprising plate means including a first pair of flat hexagonally shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer 'mounted between said hexagonally shaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equal dimension defining the substantially parallel separation between said first plates.

20. A tuning element comprising an integrally constructed shorting assembly having proximate one end thereof a drive arrangement including a set of drive rollers and a first shorting brush configuration, proximate the other end thereof a guide arrangement including a set of guide rollers and a second shorting brush configuration, and an intermediate brush arrangement predeterminably arranged as to said shorting assembly between said drive and guide arrangements, and wherein said drive assembly is adapted to function within a helically coiled wire and is comprised of first plate means, which include a first pair of flat plates arranged to be substantially in parallel, and a plurality of roller assemblies, each having a roller and being mounted between said first pair of plates each said roller extending partially beyond said first plates for engagement with said helix and being predeterminably positioned so as to have the rollers of said plurality of assemblies helically staggered between said first plates, and wherein said guide arrangement is adapted to function within and engage a cylindrically shaped surface and comprising plate means including a first pair of fiat hexagonally shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer mounted between said hexagonally shaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equal dimension defining the substantially parallel separation between said first plates.

21. A tuning element comprising an integrally constructed shorting assembly having proximate one end thereof a drive arrangement including a set of drive rollers and a first shorting brush configuration, proximate the other end thereof a guide arrangement including a set of guide rollers and a second shorting brush configuration, and an intermediate brush arrangement predeterminably arranged asto said shorting assembly between said drive and guide arrangements, and wherein said drive assembly is adapted to function within a helically coiled wire and is comprised of first plate means, which include a first pair of flat plates arranged to be substantially in parallel, and a plurality'of rollerassemblies, each having a roller and being mounted between said first pair of plates, each said roller extending partially beyond said first plates for engagement with said helix and being predeterminably positioned so as to have the rollers of said plurality of assemblies helically staggered between said first plates, and wherein said guide arrangement is adapted to function within and engage a cylindrically shaped surface and comprising plate means including a first pair of flat hexagonally shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer mounted between said hexagonally shaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equal dimension defining the substantially parallel separation between said first plates, and wherein said intermediate brush arrangement includes at least one shorting brush configuration mounted radially on a cylindrical middle portion of said shorting assembly, said intermediate shorting bursh configuration having a tubular outer structure and a brush element mounted within said tubular structure so as to partially protrude therefrom and to be resiliently displaceable therein. 

1. In a drive assembly adapted to function within a helically coiled wire, the arrangement comprising first plate means including a first pair of flat plates arranged to be substantially in parallel and a plurality of roller assemblies, each having a roller and being mounted between said first pair of plates, each said roller assembly including an axle arranged to extend between said first plates proximate the peripheries of the latter, with the associated roller being arranged on said axle, and a roller spacer set arranged on said axles and between said first plates to helically position said rollers between said plates to extend outwardly thereof and engage the helically coiled wire.
 2. The arrangement of claim 1 wherein said roller assemblies are mounted between said first plates to be equally spaced apart from one another.
 3. The arrangement of claim 2 wherein each said spacer set includes a spacer member of predetermined size on either or both sides of the associated roller so as to provide the latter with said predetermined position between said first plates.
 4. The arrangement of claim 3 wherein said spacer member is comprised of one or more unit-sized spacers, the unit size of which is predetermined by the pitch of said helix and the number of roller assemblies employed.
 5. The arrangement of claim 1 wherein said rollers are arranged to be staggered helically in pitch between said first plates by way of said spacer set so as to have said rollers engage a plurality of adjacent helix turns simultaneously.
 6. The arrangement of claiM 5 wherein in the case of said rollers engaging a pair of adjacent helix turns simultaneously, the roller assemblies are arranged to have alternate ones thereof engage the same one of said pair of helix turns.
 7. The arrangement of claim 1 further comprising second plate means including a second pair of flat plates arranged to be substantially parallel, and to have said first plates therebetween and substantially in parallel therewith, said first and second plate means being mounted together to form an integral unit.
 8. The arrangement of claim 7 wherein said roller assemblies are mounted between said first and second pairs of plates in a manner providing a capability of translational displacement substantially parallel to the plane of said first and second plates, and further comprising spring means biasing said roller assemblies outward toward the periphery of said first plate means.
 9. The arrangement of claim 8 wherein said first and second pairs of plates are hexagonally shaped with the vertices thereof substantially aligned, and wherein the axle of each said roller assembly is arranged to engage said first and second pairs of plates proximate respective ones of the aligned plate vertices.
 10. The arrangement of claim 9 wherein said spring means includes a plurality of springs mounted between said first and second plate means, each of said springs being arranged substantially between two adjacent roller assemblies so as to urge said adjacent roller assemblies toward the periphery of said first and second plate means.
 11. The arrangement of claim 10 wherein said spring means include a first plurality of springs arranged between the pair of plates comprised of one each of said first and second pairs of plates and a second plurality of springs arranged between the pair of plates comprised of the other one of said first and second pairs of plates, and wherein a respective one of each of said first and second pluralities of springs is arranged to be between each adjacent pair of roller assemblies to engage same proximate the respective opposite ends thereof to bias the latter outwardly.
 12. The arrangement of claim 11 further including mounting means in the form of a plurality of equally spaced assembly posts extending between said first and second pairs of plates for mounting said first and second plate means into an integral unit, and wherein the individual ones of said pluralities of springs are mounted on said posts.
 13. The arrangement of claim 12 wherein one of said posts is located between each adjacent pair of roller assemblies and equidistant therefrom, and wherein said springs are correspondingly positioned between adjacent roller assemblies.
 14. The arrangement of claim 10 wherein said first and second plates are each provided with a plurality of elongated apertures each extending radially inward from a point proximate a respective one of said hexagon vertices, for permitting the axles of said roller assemblies to extend through said plates and for permitting said roller assemblies a predetermined amount of translational movement in the radial direction relative to the centers of said hexagonal plates.
 15. The arrangement of claim 14 wherein the belongated apertures in said first plates are open-ended to communicate with the periphery of said first plates, so as to enable said roller assemblies to be placed into position with ease.
 16. The arrangement of claim 12 further including conductive spring means in the form of a plurality of conductive springs one mounted on every other assembly post and arranged to engage the respective rollers of every other adjacent pair of roller assemblies, so as to render the electrical potential difference between said rollers and said plates zero.
 17. The arrangement of claim 1 further including a lower shorting brush arrangement coupled to said drive assembly arrangement, the combination forming a lower drive assembly of a shorting tube assembly comprising a tuning element in an antenna having a helical radiating element.
 18. A tuning element comprising an integrally constructed shorting assembly having proximate one end thereof a drive arrangement including a set of drive rollers and first shorting brush configuration, proximate the other end thereof a guide arrangement including a set of guide rollers and a second shorting brush configuration, and an intermediate brush arrangement predeterminably arranged as to said shorting assembly between said drive and guide arrangements, said guide arrangement being adapted to function within and engage a cylindrically shaped surface and comprising plate means including a first pair of flat hexagonally shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer mounted between said hexagonally shaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equal dimension defining the substantially parallel separation between said first plates.
 19. A tuning element comprising an integrally constructed shorting assembly having proximate one end thereof a drive arrangement including a set of drive rollers and a first shorting brush configuration, proximate the other end thereof a guide arrangement including a set of guide rollers and a second shorting brush configuration, and an intermediate brush arrangement predeterminably arranged as to said shorting assembly between said drive and guide arrangements, wherein said intermediate brush arrangement includes a tubular outer structure and a shorting brush element mounted within said tubular structure so as to partially protrude therefrom and to be resiliently displaceable therein, and wherein said guide arrangement is adapted to function within and engage a cylindrically shaped surface and comprising plate means including a first pair of flat hexagonally shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer mounted between said hexagonally shaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equal dimension defining the substantially parallel separation between said first plates.
 20. A tuning element comprising an integrally constructed shorting assembly having proximate one end thereof a drive arrangement including a set of drive rollers and a first shorting brush configuration, proximate the other end thereof a guide arrangement including a set of guide rollers and a second shorting brush configuration, and an intermediate brush arrangement predeterminably arranged as to said shorting assembly between said drive and guide arrangements, and wherein said drive assembly is adapted to function within a helically coiled wire and is comprised of first plate means, which include a first pair of flat plates arranged to be substantially in parallel, and a plurality of roller assemblies, each having a roller and being mounted between said first pair of plates each said roller extending partially beyond said first plates for engagement with said helix and being predeterminably positioned so as to have the rollers of said plurality of assemblies helically staggered between said first plates, and wheRein said guide arrangement is adapted to function within and engage a cylindrically shaped surface and comprising plate means including a first pair of flat hexagonally shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer mounted between said hexagonally shaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equal dimension defining the substantially parallel separation between said first plates.
 21. A tuning element comprising an integrally constructed shorting assembly having proximate one end thereof a drive arrangement including a set of drive rollers and a first shorting brush configuration, proximate the other end thereof a guide arrangement including a set of guide rollers and a second shorting brush configuration, and an intermediate brush arrangement predeterminably arranged as to said shorting assembly between said drive and guide arrangements, and wherein said drive assembly is adapted to function within a helically coiled wire and is comprised of first plate means, which include a first pair of flat plates arranged to be substantially in parallel, and a plurality of roller assemblies, each having a roller and being mounted between said first pair of plates, each said roller extending partially beyond said first plates for engagement with said helix and being predeterminably positioned so as to have the rollers of said plurality of assemblies helically staggered between said first plates, and wherein said guide arrangement is adapted to function within and engage a cylindrically shaped surface and comprising plate means including a first pair of flat hexagonally shaped plates arranged to be substantially in parallel with the respective vertices thereof aligned, a plurality of roller assemblies each having a roller and being mounted between said first pair of plates proximate alternate pairs of said respective aligned vertices, each said roller extending partially beyond said first plates for engagement with said cylindrically shaped surface, and a plurality of spacer assemblies each having a spacer mounted between said hexagonally shaped first plates proximate the respective pairs of aligned vertices thereof which are unassociated with said roller assemblies, said spacer assemblies providing spacers of equal dimension defining the substantially parallel separation between said first plates, and wherein said intermediate brush arrangement includes at least one shorting brush configuration mounted radially on a cylindrical middle portion of said shorting assembly, said intermediate shorting bursh configuration having a tubular outer structure and a brush element mounted within said tubular structure so as to partially protrude therefrom and to be resiliently displaceable therein. 